From: Wolfgang Bangerth Date: Tue, 2 May 2006 02:38:14 +0000 (+0000) Subject: More documentation. X-Git-Tag: v8.0.0~11821 X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e4a181f009fb9ff8797b684f40bac61b4d4a18c5;p=dealii.git More documentation. git-svn-id: https://svn.dealii.org/trunk@12956 0785d39b-7218-0410-832d-ea1e28bc413d --- diff --git a/deal.II/deal.II/include/dofs/hp_dof_levels.h b/deal.II/deal.II/include/dofs/hp_dof_levels.h index e7cd776871..36e4394b7f 100644 --- a/deal.II/deal.II/include/dofs/hp_dof_levels.h +++ b/deal.II/deal.II/include/dofs/hp_dof_levels.h @@ -34,13 +34,82 @@ namespace internal /** * Store the indices of the degrees of freedom which are located on - * objects of dimension @p N. Declare this general template + * objects of dimension @p N. We declare this general template * class, but do not actually use it. Rather, only specializations of * this class are used. + * + * The things we store here is very similar to what is stored in the + * internal::DoFHandler::DoFLevel class hierarchy (see there for more + * information, in particular on the layout of the class + * hierarchy). There are two main differences, discussed in the + * following subsections. In addition to the data already stored by + * the internal::DoFHandler::DoFLevel classes, we also have to store + * which finite element each cell uses. This is done in the + * DoFLevel<0> class, where for each cell we have an entry within the + * active_fe_indices field for each cell. + * * - * @ingroup hp + *

Offset computations

+ * + * For hp methods, not all cells may use the same finite element, and + * it is consequently more complicated to determine where the DoF + * indices for a given line, quad, or hex are stored. As described in + * the documentation of the internal::DoFHandler::DoFLevel class, we + * can compute the location of the first line DoF, for example, by + * calculating the offset as line_index * + * dof_handler.get_fe().dofs_per_line. This of course doesn't + * work any more if different lines may have different numbers of + * degrees of freedom associated with them. Consequently, rather than + * using this simple multiplication, each of the line_dofs, quad_dofs, + * and hex_dofs arrays has an associated array line_dof_offsets, + * quad_dof_offsets, and hex_dof_offsets. The data corresponding to a + * line then starts at index line_dof_offsets[line_index] + * within the line_dofs array. + * + * + *

Multiple data sets per object + * + * If an object corresponds to a cell, the global dof indices of this + * cell are stored at the location indicated above in sequential + * order. + * + * However, if two adjacent cells use different finite elements, then + * the face that the share needs to store DoF indices for both + * involved finite elements. While faces therefore have to have at + * most two sets of DoF indices, it is easy to see that vertices for + * example can have as many sets of DoF indices associated with them + * as there are adjacent cells, and the same holds for lines in 3d. * - * @author Wolfgang Bangerth, 1998, Oliver Kayser-Herold 2003. + * Consequently, for objects that have a lower dimensionality than + * cells, we have to store a map from the finite element index to the + * set of DoF indices associated. Since real sets are typically very + * inefficient to store, and since most of the time we expect the + * number of individual keys to be small (frequently, adjacent cells + * will have the same finite element, and only a single entry will + * exist in the map), what we do is instead to store a linked list. In + * this format, the first entry starting at position + * line_dofs[line_dof_offsets[line_index]] will denote + * the finite element index of the set of DoF indices following; after + * this set, we will store the finite element index of the second set + * followed by the corresponding DoF indices; and so on. Finally, when + * all finite element indices adjacent to this object have been + * covered, we write a -1 to indicate the end of the list. + * + * Access to this kind of data, as well as the distinction between + * cells and objects of lower dimensionality are encoded in the + * accessor functions, DoFLevel<1>::set_line_dof_index(), + * DoFLevel<1>::get_line_dof_index(), + * DoFLevel<2>::set_quad_dof_index(), + * DoFLevel<2>::get_quad_dof_index(), and + * DoFLevel<3>::set_hex_dof_index(), + * DoFLevel<3>::get_hex_dof_index(). The are able to traverse this + * list and pick out or set a DoF index given the finite element index + * and its location within the set of DoFs corresponding to this + * finite element. + * + * + * @ingroup hp + * @author Wolfgang Bangerth, 1998, 2006, Oliver Kayser-Herold 2003. */ template class DoFLevel @@ -56,15 +125,12 @@ namespace internal /** - * Store all information which belongs to one level of the multilevel - * hierarchy. - * - * In @ref{DoFLevel<0>} all data is stored which is not dependent on the - * dimension, e.g. a field to store the index referring to the - * hp::FECollection class. The data therefore corresponds to cells, rather - * than vertices, lines, quads, etc. + * Storage for degrees of freedom on cells. See the documentation of + * the DoFLevel class template for more complete information on the + * purpose and layout of this class. * * @ingroup hp + * @author Wolfgang Bangerth, 1998, 2006, Oliver Kayser-Herold 2003. */ template <> class DoFLevel<0> @@ -90,69 +156,22 @@ namespace internal /** * Store the indices of the degrees of freedom which are located on - * the lines. - * - * @sect3{Information for all DoFLevel classes} - * - * The DoFLevel classes - * store the global indices of the degrees of freedom for each cell on a - * certain level. The index or number of a degree of freedom is the zero-based - * index of the according value in the solution vector and the row and column - * index in the global matrix or the multigrid matrix for this level. These - * indices refer to the unconstrained vectors and matrices, where we have not - * taken account of the constraints introduced by hanging nodes. If more than - * one value corresponds to one basis function, for example for vector equations - * where the solution is vector valued and thus has several degrees of freedom - * for each basis function, we nonetheless store only one index. This can then - * be viewed as the index into a block vector, where each block contains the - * different values according to a degree of freedom. It is left to the derived - * classes, whether the values in a block are stored consecutively or distributed - * (e.g. if the solution function is u=(u_1, u_2), we could store the values - * in the solution vector like - * \f[\ldots, u_1^m, u_2^m, u_1^{m+1}, u_2^{m+1},\ldots\f] with m denoting the - * m-th basis function, or - * \f[\ldots, u_1^m, u_1^{m+1}, u_1^{m+2}, \ldots, u_2^m, u_2^{m+1}, u_2^{m+2}, \ldots,\f] - * respectively). Likewise, the constraint matrix returned by - * DoFHandler::make_hanging_node_constraints () - * is then to be understood as a block matrix. - * - * The storage format of the degrees of freedom indices (short: DoF - * indices) is somewhat like a mirror of the data structures of the - * triangulation classes. There is a hierarchy of - * DoFLevel classes for the different dimensions which - * have objects named @p line_dofs, @p quad_dofs and so on, in which - * the indices of DoFs located on lines and quads, respectively, are - * stored. The indices are stored levelwise. + * the lines. See the general template DoFLevel for more information. * - * Due to the fact that different elements could have a different number - * of DoFs on each line, the DoFs on each line are stored in a nested data - * structure. @p dof_line_index_offset is used to find the start of the - * DoFs indices inside @p line_dofs. Hence the retrieval of DoF indices - * for a specific line @p i is a two step process: - * 1. Determine the index @p j in @p line_dofs, as the @p ith element of - * @p dof_line_index_offset - * 2. Get the DoF indices starting from the @p jth element in @p line_dofs. - * - * The DoF indices for vertices are not stored this way, since they - * need different treatment in multigrid environments. If no multigrid - * is used, the indices are stored in the @p vertex_dofs array of the - * DoFHandler class. - * - * * @ingroup hp - * @author Wolfgang Bangerth, 1998, Oliver Kayser-Herold 2003. + * @author Wolfgang Bangerth, 1998, 2006, Oliver Kayser-Herold 2003. */ template <> class DoFLevel<1> : public DoFLevel<0> { - public: + private: /** * Store the start index for * the degrees of freedom of each * line in the @p line_dofs array. */ - std::vector dof_line_index_offset; + std::vector line_dof_offsets; /** * Store the global indices of @@ -162,6 +181,33 @@ namespace internal */ std::vector line_dofs; + public: + + /** + * Set the global index of + * the @p local_index-th + * degree of freedom located + * on the line with number @p + * line_index to the value + * given by the last + * argument. The @p + * dof_handler argument is + * used to access the finite + * element that is to be used + * to compute the location + * where this data is stored. + * + * The third argument, @p + * fe_index, denotes which of + * the finite elements + * associated with this + * object we shall + * access. Refer to the + * general documentation of + * the internal::hp::DoFLevel + * class template for more + * information. + */ template void set_line_dof_index (const ::hp::DoFHandler &dof_handler, @@ -170,6 +216,29 @@ namespace internal const unsigned int local_index, const unsigned int global_index); + /** + * Return the global index of + * the @p local_index-th + * degree of freedom located + * on the line with number @p + * line_index. The @p + * dof_handler argument is + * used to access the finite + * element that is to be used + * to compute the location + * where this data is stored. + * + * The third argument, @p + * fe_index, denotes which of + * the finite elements + * associated with this + * object we shall + * access. Refer to the + * general documentation of + * the internal::hp::DoFLevel + * class template for more + * information. + */ template unsigned int get_line_dof_index (const ::hp::DoFHandler &dof_handler, @@ -183,28 +252,35 @@ namespace internal * of this object. */ unsigned int memory_consumption () const; + + /** + * Make the DoFHandler class + * a friend, so that it can + * resize arrays as + * necessary. + */ + template friend class ::hp::DoFHandler; }; /** * Store the indices of the degrees of freedom which are located on - * quads. See @ref{DoFLevel<1>} for more information. - * - * @ingroup hp + * quads. See the general template DoFLevel for more information. * - * @author Wolfgang Bangerth, 1998, Oliver Kayser-Herold 2003. + * @ingroup hp + * @author Wolfgang Bangerth, 1998, 2006, Oliver Kayser-Herold 2003. */ template <> class DoFLevel<2> : public DoFLevel<1> { - public: + private: /** * Store the start index for * the degrees of freedom of each * quad in the @p quad_dofs array. */ - std::vector dof_quad_index_offset; + std::vector quad_dof_offsets; /** * Store the global indices of @@ -214,6 +290,33 @@ namespace internal */ std::vector quad_dofs; + public: + + /** + * Set the global index of + * the @p local_index-th + * degree of freedom located + * on the quad with number @p + * quad_index to the value + * given by the last + * argument. The @p + * dof_handler argument is + * used to access the finite + * element that is to be used + * to compute the location + * where this data is stored. + * + * The third argument, @p + * fe_index, denotes which of + * the finite elements + * associated with this + * object we shall + * access. Refer to the + * general documentation of + * the internal::hp::DoFLevel + * class template for more + * information. + */ template void set_quad_dof_index (const ::hp::DoFHandler &dof_handler, @@ -222,6 +325,29 @@ namespace internal const unsigned int local_index, const unsigned int global_index); + /** + * Return the global index of + * the @p local_index-th + * degree of freedom located + * on the quad with number @p + * quad_index. The @p + * dof_handler argument is + * used to access the finite + * element that is to be used + * to compute the location + * where this data is stored. + * + * The third argument, @p + * fe_index, denotes which of + * the finite elements + * associated with this + * object we shall + * access. Refer to the + * general documentation of + * the internal::hp::DoFLevel + * class template for more + * information. + */ template unsigned int get_quad_dof_index (const ::hp::DoFHandler &dof_handler, @@ -235,29 +361,36 @@ namespace internal * of this object. */ unsigned int memory_consumption () const; + + /** + * Make the DoFHandler class + * a friend, so that it can + * resize arrays as + * necessary. + */ + template friend class ::hp::DoFHandler; }; /** * Store the indices of the degrees of freedom which are located on - * hexhedra. See @ref{DoFLevel<1>} for more information. - * - * @ingroup hp + * hexhedra. See the general template DoFLevel for more information. * - * @author Wolfgang Bangerth, 1998, Oliver Kayser-Herold 2003. + * @ingroup hp + * @author Wolfgang Bangerth, 1998, 2006, Oliver Kayser-Herold 2003. */ template <> class DoFLevel<3> : public DoFLevel<2> { - public: + private: /** * Store the start index for * the degrees of freedom of each * hex in the @p hex_dofs array. */ - std::vector dof_hex_index_offset; + std::vector hex_dof_offsets; /** * Store the global indices of @@ -267,6 +400,33 @@ namespace internal */ std::vector hex_dofs; + public: + + /** + * Set the global index of + * the @p local_index-th + * degree of freedom located + * on the hex with number @p + * hex_index to the value + * given by the last + * argument. The @p + * dof_handler argument is + * used to access the finite + * element that is to be used + * to compute the location + * where this data is stored. + * + * The third argument, @p + * fe_index, denotes which of + * the finite elements + * associated with this + * object we shall + * access. Refer to the + * general documentation of + * the internal::hp::DoFLevel + * class template for more + * information. + */ template void set_hex_dof_index (const ::hp::DoFHandler &dof_handler, @@ -275,6 +435,29 @@ namespace internal const unsigned int local_index, const unsigned int global_index); + /** + * Return the global index of + * the @p local_index-th + * degree of freedom located + * on the hex with number @p + * hex_index. The @p + * dof_handler argument is + * used to access the finite + * element that is to be used + * to compute the location + * where this data is stored. + * + * The third argument, @p + * fe_index, denotes which of + * the finite elements + * associated with this + * object we shall + * access. Refer to the + * general documentation of + * the internal::hp::DoFLevel + * class template for more + * information. + */ template unsigned int get_hex_dof_index (const ::hp::DoFHandler &dof_handler, @@ -288,6 +471,14 @@ namespace internal * of this object. */ unsigned int memory_consumption () const; + + /** + * Make the DoFHandler class + * a friend, so that it can + * resize arrays as + * necessary. + */ + template friend class ::hp::DoFHandler; };